Amomum raoii V.P. Thomas & M. Sabu, 2020

Thomas, V. P., Sabu, M., Jayakrishnan, T. & Rajeesh, E. P., 2020, A new species and a new combination of Amomum Roxb. (Zingiberaceae) from Sikkim Himalaya, India, Phytotaxa 430 (1), pp. 46-50 : 46-48

Amomum raoii V.P. Thomas & M. Sabu , sp. nov. ( Fig. 1 )

Amomum kingii auct . non Baker.: Thomas & Sabu (2015:7034).

Similar to Amomum sabuanum V.P.Thomas, Nissar & U. Gupta (2014:122) but differs from it in having white flowers tinged with yellow, single flower in a bract, longer peduncle (5.5−9 cm), 3-lobed calyx, longer lateral staminodes (1.6−1.7 cm) and globose fruits without an apical depression.

Type:— INDIA. Sikkim: East Sikkim District, Pangthang, alt. 1890 m, 7 May 2007, V. P. Thomas & V. A. Muhammed Nissar 95505 (holotype CALI!, isotype CAL!, CATH!).

Rhizome stout, c. 5 cm thick, covered with coriaceous, glabrous sheaths. Leafy shoots 200–350 cm tall; sheath c. 4 cm wide at base, maroon, lined with prominent parallel veins, margin membranous, glabrous externally. Leaves 6–8 per tiller; lamina oblong-lanceolate, 55–120 × 17.5–24 cm, dark green above, powdery white beneath, base oblique, apex acuminate, glabrous on both surfaces; midrib pink, glabrous except a layer of hairs along the margin beneath; petiole 0.8–1.3 cm long, pale pink, puberulous inside, glabrous externally. Ligule entire, 1–1.5 cm long, coriaceous, dark maroon, margin ciliate, apex rounded, externally pubescent, dark maroon glandular structure present in adjoining portion of petiole and ligule. Inflorescence 13–25 × 4–7.5 cm, radical, oblong; peduncle 5.5–9 cm long. Sheathing bract 8–9 per inflorescence, ovate, brown, 5–7 × 3–5 cm, laterally fused with adjacent bracts, prominently veined, puberulous externally, glabrous within. Flower 4.5–5.7 cm long, white tinged with yellow, many blooms at a time. Bracts linear lanceolate, 3.5–3.9 × 0.7–1 cm, membranous, pale yellow, margin distantly ciliate, apex acute, pubescent externally, glabrous within. Bracteole highly reduced, represented by small rudimentary structures, irregular in shape, c. 0.2 × 0.3 cm, open or fused by ends, margin distantly ciliate, apex acute, glabrous. Calyx 3-toothed, 2.3–3.2 × 0.8 cm, white, membranous, lobes pubescent, cleft 1.2–1.4 cm deep, apex acute, pubescent externally, glabrous within. Corolla tube 2.2–2.3 cm long, 0.4–0.5 cm wide at mouth, pale yellow, densely pubescent externally, pubescent within, densely towards mouth; dorsal corolla lobe oblong, 2.1–2.5 × 1.2–1.3 cm, white tinged with pink, margin ciliate near base, apex hooded, densely pubescent externally, glabrous within; lateral corolla lobes oblong, 2–2.2 × 0.9–1.1 cm, white tinged with pink, margin ciliate towards base, apex form a folding, pubescent externally, glabrous within. Labellum obovate, 3–5 × 2.6–2.8 cm, obscurely 3-lobed, median lobe emarginate, cleft c. 0.5 cm deep, white tinged with yellow, centre with dark pink bands which arise from base, bands divides at different levels, basal part formed of red, margin crenulate, pubescent inside towards base. Lateral staminodes ribbon-like, 1.5–1.8 cm long, flat, tapering towards apex, pale yellow, lower part maroon, densely pubescent towards base, glabrous towards apex. Stamen 2.3– 2.5 cm long; filament 0.5–0.6 × 0.4–0.6 cm, creamy white, pink towards base, pubescent externally, pubescent within; connective glandular hairy; crest obscurely tri-lobed with unequal lobbing, 1.3–1.5 × 0.7–0.9 cm, white, glabrous within, puberulous externally; anther 2-celled, thecae oblong, 1.1–1.3 cm, cream coloured, base sharply ending, apex diverging, margin glabrous, dehiscence complete, linear. Epigynous glands 2, oblong, 0.6–0.7 cm long, cream coloured, rarely gland not completely separated. Ovary inferior, 0.5–0.7 × 0.5–0.6 cm, trigonous, glabrous externally; pedicel hairy; locules 3; ovules many on axile placentae, two in each row; style c. 3.6 cm long, glabrous; stigma c. 0.1 cm, cup-shaped, white, mouth ciliate, opening apical. Infructescence c. 14 cm long, peduncle c. 7 cm long, 10–15 per spike. Capsule globose or spherical, 2.4–2.7 × 2.5–2.6 cm, smooth walled, red tinged with green, glabrous. Seeds many, 0.4–0.6 × 0.3–0.4 cm, brown, aromatic, glabrous, arillate; aril white.

Flowering: — March–May.

Fruiting: — June–August.

Ecology:— In shaded places at high altitudes (above 1800 m asl) in Sikkim.

Etymology:—The specific epithet is in honour of Dr. Raghavendra R Rao, CIMAP, Bangaluru for his contributions in the field of Taxonomy.

Additional specimens examined:— INDIA, Sikkim, East Sikkim district: Pangthang , 23 August 2004, M. Sabu & A. K. Pradeep 92731 ( CALI) ; 04 November 2005, E. Sanoj 92778 ( CALI) ; 22 August 2006, V. P. Thomas 105504 ( CALI) .

Figures

FIGURE 1. Amomum raoii. A. a part of leafy shoot; B. ligule; C. inflorescence; D. outer bract; E. bracteole; F. flower; G. calyx; H. corolla lobes; I. stamen; J. labellum; K. ovary with epigynous glands and style; L. stigma; M. c.s. of ovary; N. fruit; O. seed. Drawn by V.P. Thomas.